1. Field of the Invention
Embodiments of the present invention relate to a manufacturing method of an integrated foam-molded product and an integrated foam-molded product, and more particularly relate to a manufacturing method for obtaining an integrated foam-molded product with a polyurethane foam layer, and an integrated foam-molded product.
2. Description of the Related Art
As a seat cushion, a seat back, a headrest, and so on of a vehicle seat, a skin-integrated foam-molded product whose skin layer and polyurethane foam layer are molded by integrated foaming is known. For example, Patent Document 1 and Patent Document 2 disclose those in which a skin material, a wadding material, a resin film (raw material shielding layer), and polyurethane foam as a cushion material are stacked, and the resin film is used in order to prevent a foamable raw material of the polyurethane foam from permeating the wadding material.
Further, foaming heat and carbon dioxide gas are generated during the foam-molding of the polyurethane foam raw material, though not explicitly pointed out in Patent Documents 1, 2. The foaming heat sometimes damages the skin material, and the carbon dioxide gas increases an internal pressure in a mold, which sometimes causes the generation of voids and the like. Therefore, the exhaust from an exhaust hole provided in an upper mold is generally performed during the manufacture. However, there is a problem of leakage of the foaming polyurethane foam raw material through this exhaust hole, and in order to prevent such problems, Patent Document 3 proposes a molding method in which a skin layer having air permeability is provided on an upper mold in which an exhaust hole is formed.
Patent Document 1: Japanese Patent Application Laid-open No. 2003-94543
Patent Document 2: Japanese Patent Application Laid-open No. 2004-268406
Patent Document 3: Japanese Patent Application Laid-open No. Hei 3-41992
As is apparent from the fact that Patent Document 3 proposes the way to smoothly perform the exhaust from the exhaust hole, when the polyurethane foam layer and the other members are integrated, the foaming is heat and the gas (carbon dioxide gas) generated at the time of the foaming of the polyurethane foam raw material cause the occurrence of a defect in a molded product, and at a manufacturing and development site, it has conventionally been a general practice to put an importance on minimizing influences of these.
Further, the other members integrated with the polyurethane foam layer, for example, the skin material, the wadding material, and so on are basically only adhering to the polyurethane foam layer, and their shapes are in principle fixed in a working step prior to the foam molding, though influenced by a foaming pressure of the polyurethane foam raw material. Therefore, at the time of the foam molding, it has been necessary to contrive a measure, such as the smooth exhaust from the exhaust hole, in order to prevent the aforesaid foaming heat and gas from affecting the other members that are to be integrated.